The present invention relates to a golf ball and, more particularly, relates to a golf ball formed with dimples and lands on the surface thereof to increase the flight distance.
It has been well known that in designing a golf ball, the high resilience performance that the golf ball itself has and a decrease in air resistance during flight caused by the dimples arranged on the surface of the golf ball are of importance in obtaining a long flight distance when the golf ball is hit. Usually, a large number of dimples is arranged on the surface of a golf ball, and it has been thought that as the surface occupancy ratio of the dimples increases, the aerodynamic performance of golf ball is improved. Therefore, to improve aerodynamic performance, various methods for arranging dimples on the surface of golf ball at a high density have been proposed.
Usually, in designing the dimples of a golf ball, there has been used a method in which dimples having predetermined one or a plurality of shapes are arranged on the surface of the golf ball. In the method in which dimples having such predetermined shapes are arranged, however, if the surface occupancy ratio of the dimples increases greatly, it is difficult to arrange the dimples uniformly because the surface of the golf ball is spherical. Therefore, locations in which a gap between dimples widens or narrows are produced, and the gap between dimples often is nonuniform. If the gap between dimples is nonuniform, there is a possibility that the aerodynamic performance of the golf ball will be extremely poor even if the surface occupancy ratio of the dimples is high.
Japanese Unexamined Patent Application Publication No. 2004-105200 and Japanese Unexamined Patent Application Publication No. 2004-141467 disclose techniques in which ridge-shaped protrusions are formed on the surface of a golf ball, the techniques being entirely different from the conventional idea that a large number of dimples are formed at the surface of a golf ball. By forming the ridge-shaped protrusions in this manner, the occupancy ratio of portions having no protrusions, which corresponds to the conventional surface occupancy ratio of the dimples, can be increased easily, and thereby the aerodynamic performance can be improved.